Updating page editor hooks for v4.9.3
From Sohowiki
The Easy Way To Update
Within your object javascript simply add the following to the end, that is, after you have placed your object into the cell.
if ( window.checkPageAreas ){ checkPageAreas('start'); }
And thats it.
Final note
The new page_editor.php uses a XHTML 1.0 Strict doctype and may effect the look/feel of your properties layer.